Donohue syndrome (Leprechaunism) is characterized by severe insulin resistance, hyperinsulinemia, postprandial hyperglycemia, preprandial hypoglycemia, intrauterine and postnatal growth retardation, dysmorphic findings, and clinical and laboratory findings of hyperandrogenemia due to homozygous or compound heterozygous inactivating mutations in the insulin receptor gene. A female newborn presented with lack of subcutaneous fat tissue, bilateral simian creases, hypertrichosis, especially on her face, gingival hypertrophy, cliteromegaly, and prominent nipples. Her laboratory tests revealed hyperandrogenism, postprandial hyperglycemia and preprandial hypoglycemia, and very high concurrent insulin levels. She was diagnosed as having Donohue syndrome. Metformin and continuous nasogastric feeding were administrated. During follow-up, relatively good glycemic control was obtained. However, severe hypertrophic obstructive cardiomyopathy and severe malnutrition developed. She died aged 75 days of severe heart failure and pneumonia. Her INSR gene analysis revealed a compound heterozygous mutation. One of these mutations was a p.R813 (c.2437C>T) mutation, which was defined previously and shown also in her father, the other mutation was a novel p.777-790delVAAFPNTSSTSVPT mutation, also shown in her mother. The parents were heterozygous for these mutations.